Answer:
521,500 or 5.215 x 10^5
Explanation:
A quick way to solve something that is multiplied by 10^n, simply move the decimal point the same number as n. (For example, 1.6 x 10^3 simply move the decimal to the right 3 times 1600.0)
Therefore,
15 x 10^2 = 1500
5.2 x 10^5 = 520000
1500 + 520000 = 521500 or 5.215 x 10^5